Extract renderGrid state/repaint wiring before Panels (#167)

[BorisTyshkevich]

What & why

Closes #167 — the behavior-preserving preparation step for the Panels track (#166).

The complex grid surface was already shared (renderGrid), but its state wiring ({sort, widths} holder + repaint-on-sort closure) was hand-rolled at three sites, each slightly different. This PR:

• New module src/ui/grid-render.js — renderGrid (moved verbatim, stays stateless; onCell is now optional so a consumer without a cell-detail surface degrades safely instead of throwing), colResizeWidth, the column-resize logic behind two shared helpers (resizeHandle, reapplyWidths — the 8-line handle span + reapply guard were previously copy-pasted three times), PLAIN_KEY, GRID_VIS_CAP, and the new renderGridView adapter with the issue's explicit seams (sort/setSort/widths/rerender/onCell/cap): setSort is called exactly once per sort click, rerender after the state update, widths passes through by reference. No dependency back into results.js (prevents the results → panels → renderer → results cycle Extract the renderGrid local-state wiring (sort/widths + repaint) — four hand-rolled copies #167 called out).
• Three consumers migrated to renderGridView, each preserving its exact state lifetime and repaint scope: main results table (app.state.resultSort + r.colWidths, full renderResults repaint, visCap(r)), script-result rows viewer (entry-persisted state, drawer-body repaint), detached Data pane (snapshot-local state, caller-owned Table/JSON/Chart repaint + Chart.js cleanup, detached-document cell detail). The script grids reuse the shared resize helpers with PLAIN_KEY.
• Tests — new per-module spec tests/unit/grid-render.test.js (adapter contract per the issue's Tests section + grid/resize mechanics; 100/100/100/100). results.test.js keeps the wiring-level specs and gains coverage for the toolbar Expand button and the script-grid resize-handle click — the extraction exposed them as the file's only uncovered functions, along with two unreachable no-op cancelDrawerDrag initializers (always reassigned before any close can fire), now removed per the repo's no-dead-defensive-code philosophy.

Explicitly out of scope (per the issue): panel/dashboard/saved-query knowledge, gridStateForSchema (deferred until #166 has a consumer), and any sorting/resizing behavior change. visCap stays in results.js (it's result-shaped policy; the adapter takes cap as an input).

Reviewed via an 8-angle finder/verify pass; three confirmed findings (test duplication, unguarded optional onCell, thrice-copied resize wiring) are fixed in this diff.

Checklist

• npm test passes (2118 tests; grid-render.js at 100/100/100/100, results.js within the gate)
• Tests added/updated in the same change as the code
• npm run build succeeds (single-file dist/sql.html)
• Layers kept honest: DOM render in src/ui/, state seams injected by the caller; no src/core//src/net/ changes
• No new runtime dependency
• CHANGELOG.md ([Unreleased]) updated
• Reconciled affected tracked work: Roadmap to 1.0.0 #68's Phase 6 entry is this issue (checked off on merge); Panels: visualization registry + Panel drawer tab + Library panel field #166's integration contract is satisfied as written

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https://claude.ai/code/session_01KvqMJNyxUAJQcEm1Tn29Qr